1. Field of the Invention
The present invention relates to a fuel injection controller for an internal combustion engine and more particularly to a control of a fuel injection quantity in an inlet pipe injection type internal combustion engine that injects fuel to an inlet passage.
2. Description of the Related Art
For instance, as a traveling drive source of a motor vehicle, an inlet pipe injection type internal combustion engine for injecting fuel into an inlet pipe in the upstream side of a fuel injection valve has been hitherto widely employed. In such an internal combustion engine, a fuel injection quantity is controlled in accordance with an operating condition such as an inlet air quantity.
However, a part of the fuel injected from the fuel injection valve may possibly adhere to an inner wall of the inlet pipe. Further, the fuel adhering to the inner wall of the inlet pipe may sometimes evaporate to be transported to a cylinder. Therefore, even when the fuel injection quantity is controlled on the basis of the inlet air quantity, the fuel transported to the cylinder may be insufficient or excessive. Thus, there is a fear that an accident fire may be caused or an exhaust performance may be deteriorated.
Thus, a technique is developed that the fuel adhering to the wall of the inlet pipe and an evaporating part of the fuel adhering to the wall are predicted and the fuel injection quantity from the fuel injection valve is determined by considering the predicted quantities thereof, as disclosed in JP-A-2005-188293.
In the inlet pipe injection type internal combustion engine, the fuel is ordinarily injected during a closing state of an inlet valve. When a large quantity of fuel injection is required, the fuel is injected not only during the closing state of the inlet valve, but also during the opening state of the inlet valve. However, since the flowing state of inlet air in the inlet pipe is extremely different between the opening state of the inlet valve and the closing state of the inlet valve, transport characteristics of the fuel to the cylinder are greatly changed.
Accordingly, as in the above-described patent literature 1, even when the fuel adhering to the wall of the inlet pipe and an evaporating part of the fuel adhering to the wall are predicted and the fuel injection quantity from the fuel injection valve is determined simply by considering the predicted quantities thereof, it is difficult to precisely transport a desired quantity of fuel into the cylinder especially during a transient operation in which the intake air quantity varies.